Arsia Mons Flank
About this image
The three large aligned Tharsis volcanoes are Arsia Mons, Pavonis Mons and Ascreaus Mons (from south to north). There are collapse features on all three volcanoes, on the southwestern and northeastern flanks. This alignment may indicate a large fracture/vent system was responsible for the eruptions that formed all three volcanoes. This VIS image shows part of the southern flank of Arsia Mons, along the center of the aligned fracture system. The scalloped depressions are most likely created by collapse of the roof of lava tubes. Lava tubes originate during eruption event, when the margins of a flow harden around a still flowing lava stream. When an eruption ends these can become hollow tubes within the flow. With time, the roof of the tube may collapse into the empty space below. The tubes are linear, so the collapse of the roof creates a linear depression. In this region, the complexity of the collapse and faulting has created a unique surface. This region has collapse depressions with floors at a variety of elevations and depression sizes from small to large.
Arsia Mons is the southernmost of the Tharsis volcanoes. It is 270 miles (450km) in diameter, almost 12 miles (20km) high, and the summit caldera is 72 miles (120km) wide. For comparison, the largest volcano on Earth is Mauna Loa. From its base on the sea floor, Mauna Loa measures only 6.3 miles high and 75 miles in diameter. A large volcanic crater known as a caldera is located at the summit of all of the Tharsis volcanoes. These calderas are produced by massive volcanic explosions and collapse. The Arsia Mons summit caldera is larger than many volcanoes on Earth.
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